Method of removing wax haze from an oil



arch 3, 1936., R WATTS ET AL 2,033,057

METHOD OF REMOVING WAX HAZE FROM AN OIL Filed D30. 27, 1933 REVOAV/A G W514 TIA/G CHA MBER 'W A TING COIL F/L EQ 1:;-

COOLER.

Patented Mar. 3, 1936 UNET STATES METHOD OF REMOVING AN OIL Rhea N. Watts and WAX HAZE FROM John MoA. Harris, Jr.,

Baton Rouge, La., assignors to Standard-I. .6.

Company Application December 27, 1933, Serial No.'704,130

7 Claims.

This invention relates to lubricating oils, particularly those prepared by hydrogenation or destructive hydrogenation processes or by synthetic means.

It has been found that lubricating oils prepared "by synthetic or hydrogenation processes frequently tend to become hazy on standing at temperatures slightly below normal such as prevail during the winter months. The recent trend toward dispensing lubricating oils in transparent bottles has drawn attention to this peculiarity.

The hazy appearance of these oils is apparently most often due to the presence therein of small quantities of high molecular weight waxes which separate from the oil on standing in the form of fiocs. These fiocs impart to the oil a hazy or cloudy appearance. Their presence in the oil does not affect its lubricating qualities but the appearance. of a haze is objectionable from a marketing standpoint because-it leads the customer to believe that the oil has not been properly finished.

The term haze as used in this specification is not to be confused with cloud which appears in lubricating oils when chilled to within 10 .F or so of their pour points. Haze may appear in an oil of low pour point even when allowed to stand at a temperature well above its pour point, say at 90 F. or more.

It is a principal object of the present invention to provide a method for dehazing such oils, that is to remove the haze-forming constituents. It has been observed that the ordinary methods of treating and finishing lubricating oils do not adequately remove the haze. 'Itis therefore necessary to provide special treatment for this purpose.

There are in general three distinct types of haze. These are (a) wax haze, (b) moisture haze and 0) oxidation haze. Wax haze appears in the form of large fiuffy flocs which do not settle out on standing. Moisture haze appears as an evenly distributed cloudiness which does not change materially on standing except that Numeral I designates a furnace setting where heat is supplied by means of a burner 2. Oil that is to be heated is circulated through the furnace by means of pipe 3 which is equipped with a plurality of outlets and valves 4 and 5. The heated oil is passed into treating chamber 6, which is provided with a stirrer 'l operated by motor :8. A revolving drum 9, provided with a furnace setting I0 is heated by means of burner l I Into this revol-v'ing drum is passed clay from bin l2 through pipe l3. A valve I4 is provided to regulate the amount of clay passing into the revolving drum 9. The clay passing through revolving drum '9 is heated to a temperature between about 250 and 350 F., preferably 300 F., and passed through the inlet I 5 into the treating drum 6. The oil which has passed through the furnace l is also raised toa similar temperature. The oil and clay mixture in the treating chamber '15 is stirred by means of a stirrer 1 to obtain better contact. "The temperature in the treating chamber 6 maintained, preferably about 300" F., by "means of steam coils l6, through which superheated steam is circulated by means of inlet l1 and outlet l-8. The contacting of clay and oil is continued for a period of 15-30 minutes, after which the-oil and clay mixture is withdrawn by means of pipe [0, provided with valve 20, and passed through filter 2!. The oil after being separated from the clay in filter 2| is passed through pipe 22 through cooler 23 and to storage (not shown) by means of pipe 20.

The drum 9 is revolved by means of the gears 25 and motor 26. The oil that is to be treated may be continuously heated in the furnace l and a plurality of treating chambers provided in order to make the process a continuous one, as the clay heater, the filter and the cooler may be used in combination with a plurality of treated chambers.

The oil to be dehazed is heated to a temperature between about 250 and 350 F., preferably about 300 F. While maintained at this temperature the oil is contacted with an active clay, such as Attapulgus, Terrana, Floridin, Utah or other active decolorizing clays familiar in refinery practice. The clay may be separately heated to approximately the same temperature as the oil before contacting or it may be added slowly in small amounts to the oil so that the oil temperature is not substantially lowered below about 300 F. About 20 to pounds of clay per barrel of oil gives satisfactory results although smaller or larger quantities may of course be used depending upon the character of the oil to be dehazed.

The contacting is continued at a temperature of about 300 F., preferably for a period of 15 to 30 minutes, after which time the oil is withdrawn and cooled. The oil so treated shows no tendency to haze at temperatures of 30 F. or lower.

In carrying out the method, the oil to be treated is preferably first finished by the usual methods such as dewaxing, percolation through clay and reduction to proper viscosity. None of these usual treatments appear to be effective in removing the haze-forming constituents, so that the above described additional treatment is found to be necessary. 7

Whether or not an oil which has been otherwise finished will haze can be readily determined by placing a small sample in a transparent bottle and allowing it to stand for 24 to 48 hours at a temperature between 35 and 45 F. If any wax haze is present it will appear at the end of this time in the form of large white fiocs.

We are aware that other processes have previously been described in which lubricating oil is first heated to a high temperature and is thereafter contacted with clay. These already known processes, however, are described in connection with lubricating fractions obtained from petroleum by ordinary distillation methods. Such oils do not appear to contain the haze-forming constituents found in lubricating oils prepared by hydrogenation, destructive hydrogenation or synthetic processes. Moreover,'whereas the ordinary methods" of finishing applied to lubricating oils obtained by distillation produce oils that do not tend to haze on standing, the same methods applied to hydrogenated or synthetically prepared oils do not produce oils which are free from haze-forming tendencies.

As an example of the effectiveness of the present method in removing haze a synthetic oil prepared by the polymerization of cracked paraffin wax which has a marked tendency to haze at room temperature is first heated to 300 F. with 20 pounds of Attapulgus clay per barrel of oil and contacted at this temperature for'15 minutes. The oil is then filtered from the clay and is found to be still hazy at room temperature.

Another portion of the same synthetic oil is then heated alone to 300 F. and while at this temperature is contacted with 20 pounds of clay per barrel for 15 minutes. The oil is then filtered from the clay and is found to be free of haze at room temperature.

The above two experiments illustrate the important feature of the present invention,-namely, the heating of the oil to a temperature of about 300 F. prior to contacting with clay.

The present process of treating oils is susceptible of various modifications as will be understood. One especially useful modificationis that. in

which the oil is subjected to multiple step clay ture and subsequent treatments at successivelylower temperatures. In this way the optimum temperature for the removal of a particular material may be used. By way of example, clay treatment at a temperature of about 325 F. will remove colloidal wax, whereas clay treatment at about 240 F. will remove certain color bodies.

This invention is not limited by any theories of the mechanism of the reaction nor by any details which may have been given for purposes of illustration merely, but is limited only in and by the following claims in which it is our intention to claim all novelty inherent in the process.

We claim:

1. The method or removing wax haze from an oil of the class consisting of hydrogenated, destructively hydrogenated and synthetic oils, which has already been finished by the usual refining methods such as dewaxing, acid and clay treatment, which comprises heating the oil alone to a temperature between about 250 and 350 F., then contacting the oil while maintained at a temperature of about 300 F. with an active clay for a short period of time and filtering and cooling the oil.

2. Method according to claim 1 in which the heated oil is contacted with about 20 to 30 pounds of clay per barrel of oil.

3. Method according to claim 1 in which the heated oil is contacted with clay for a period of 15 to 30 minutes.

4. Method according to claim 1 in which said oil is a synthetic hydrocarbon lubricating oil.

5. Method according to claim 1 in which said oil is a hydrogenated petroleum oil.

6. Method according to claim 1 in which said oil is a destructively hydrogenated petroleum 1 batches of active clay at progressively decreasing temperatures above about 240 F., whereby color bodies are first removed and then the wax haze is removed.

RHEA N. WA'ITS.

JOHN McA. HARRIS, JR. 

